nanodbc was overriding the C++ standard library being used, which would
break builds with clang. Additionally, adding Werror unconditionally in
production code is a bad idea because different compiler versions can
change/add warnings and then break the code.
Allows placing parts from an external database that reference symbols from another loaded library.
Includes:
- nanodbc wrapper
- database schematic library plugin
- basic tests
Fixes https://gitlab.com/kicad/code/kicad/-/issues/7436